Cellulose formate.



ATES PATENT onnion SIGMUND KAI-FF, OF AACHEN, GERMANY.

CELLULOSE FORMATE.

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No Drawing. I

To all whom it may concern:

Be it known that I, SIGMUND VON KAPFF, a subject of the King ofWiirtemberg, residing at 100 Boxgraben, Aachen, Germany, haveinvented-certain new and useful Improvements Relating to CelluloseFormates; and I do hereby declare the following to be a full, clear, andexact description of the nvention.

The subject matter of my invention is animproved process of makingcellulose formate.

1 and subsequent precipitation of the It is well-known that cotton orcellulose only dissolves in formic acid when sulfuric or hydrochloricacid is added to the formic acid. There are difliculties' in recoveringsuch a mixture of inorganic acid and formic acid, and the solution ofcellulose in this mixture is subjected, owing to the presence of thestrong inorganic acid, to relatively rapid decomposition or still moreradical change which makes the em loyment of this solution for makingartificial silk either quite impossible or very diflicult and causesgreat losses. Now the inorganic acid can be separated from the solventby previously dissolving the cellulose (as such as well as in the formof cotton or of mercerized cotton or in the form of oxycellulose,hydrocellulose, hydro-oxycellulose, so thatby the term cellulose allsuch forms are included) in sulfuric acid of a definite degree ofconcentration, namely about 55 Baum, cellulose by water. The cellulosedissolved in the sulfuric acid and precipitated by water is completelyliberated from sulfuric acid by washing with Water. Nevertheless itdissolves 1n formic acid without other admixtures such as sulfuricor'hydrochloric acid bein necessary. The cellulose can be separate fromthis solution in known manner as artificial silk and the like and thesolvent canbe recovered without change and almost without loss. 7

Example: One part by weight of cellulose (e. g. cotton) is added toabout thirty parts Specification of Letters Patent.

mate and triformate, being in formic acid.

Patented Mar. 29, 1910.

Application filed July 24, 1909. Serial No. 509,385.

by weight of sulfuric acid of approximately 55 Baum until a thick,viscous paste is obtained. This is poured slowly into water, washed, andthe separated cellulose is then poured off and drled. The cellulose thusobtained dissolves in from ten to thirty minutes (varying withdifi'erent temperatures) in formic acid of approximately 100 per cent, amixture of various'cellulose formates, 2'. e. cellulose monoformate,diforformed.

The proportions stated in the example may obviously be widely varied-without aifecting the operation of the process.

I claim:

1. The hereindescribed process of making cellulose formate, whichconsists in dissolving cellulose in sulfuric acid, precipitating it fromthe solution thus obtained, separating the precipitated cellulose fromthe liquid, washing the cellulose free from sul- -furie acid, anddissolving it in formic acid.

2. The hereindescribed process of making cellulose formate, whichconsists in dissolving cellulose in sulfuric acid of approximatelyfifty-five degrees Baum, precipitating it from the solution thusobtained, sepa-.

rating the precipitated cellulose from the liquid, washing the cellulosefree from sulfuric acid, and dissolving it in formic acid.

3. The hereindescribed process of making cellulose for-mate, whichconsists in dissolving cellulose in sulfuric acid of approximatelyfifty-five degrees Baum, precipitating it from the solution thusobtained, separatin the precipitated cellulose from the liquiii washing1.1t free from sulfuric acid and drying the same, and then dissolvingit- V I have signed my name to th s specification, in the presence oftwo subscribing-witnesses.

SIGMUND v. KAPFF.

In testimony whereof Witnesses HEINRICH SoHMm, -HENRY QUADFLIEG.

